NATIONAL TRANSPORTATION SAFETY BOARD

e of Research and Engineering
Washington. D.C. 20594

February 19, 2002

Flight Path Study - United Airlines Flight 175

A. SUBJECT AIRCRAFT

Location: New York City, NY

Date: September 1 1 , 2001

Time: 09:03 AM Eastern Daylight Time

Flight: United Airlines Flight 175

Aircraft: Boeing 767

NTSB#: DCA01 MA063

B. GROUP
N/A

C. SUMMARY

This document provides a brief description of the flight path of the aircraft
based on information obtained from various sources of recorded radar of the
subject aircraft both before and after the hijacking events. Flight paths are
overlaid onto maps of the area, and time histories of altitude data are presented.

United Airlines Flight 175 — Flight Profile

The following description of United Airlines Flight 175 is based on radar data
obtained from the Federal Aviation Administration’s Air Route Traffic Control
Centers, approach control at JFK Airport, and the U.S. Air Force 84th Radar
Evaluation Squadron.

Figure 1 shows the flight path of the aircraft from take off at Boston Logan airport
to the crash site at the World Trade Center. Figure 2 shows the aircraft’s altitude
profile for the 49-minute duration of the flight.

United Airlines Flight 175 departed Boston Logan airport at 8:14 AM (point A in
Figures 1 and 2) and reached its assigned cruising altitude of 31,000 feet at

1

about 8:33 AM (B). At 8:39 AM (C), flight 175 is instructed to turn right to avoid
southbound traffic, an American Airlines 767. The final radio transmission from
UAL flight 175 occurred at 8:42 (D). The first indication of deviation from normal
routine occurred at 8:47, when the aircraft changed beacon codes twice within a
one-minute period (E). At approximately 8:51, UAL175 deviated from the
assigned altitude (F). At 8:52, FAA’s New York Center Air traffic control facility
attempted to contact the flight several times, with no response, as the aircraft
started a turn to the southeast. The aircraft continued to climb during the turn,

reaching 33,500 feet.

The airplane started to descend as it flew in a southeasterly direction. At
approximately 8:57, the airplane started a turn to the northeast, while
momentarily stopping the descent at 28,500 feet. By 8:58 (G) the aircraft was
heading towards New York City, and continued its descent. The final radar
return from United Flight 175 at JFK approach control occurred at an altitude of
1000 feet and close proximity to the World Trade Center. The airplane impacted
the south tower of the World Trade Center at approximately 9:02:40 AM.

m\ Ritter
Chief, Vehicle Performance Division

NTSB

2

United Airlines Flight 175 Ground Track

(Simple Map Background)

Figure 1 - Flight Path

United Airlines Flight 175

Pressure Altitude from Radar Mode C Returns

i_ T _r "

n — i — i — | — i — r

"I 1 1 1 1

— i — i — | — i — i — r

' 1 1

1 1 1 1

1 1 1 1

o

o

o

o

o

O

o

o

o

o

o

o

O

o

o

o

o

o

o

o

o

LO

o

LO

o

LO

o

LO

CO

CO

CM

CM

T“

T—

lo

o

O)

o

o

o

CT>

o

LO

LO

do

O

—

o

lO

CO

3

—

o

o

-

X

-

-

LO

1

o

0)

CO

1 —

a ■■■■

-

o

3

o

CL

-

o
• •

■ a

CD

■o

-

00

o

X

3

—

-

LO

CD

E

<

1

CO

j —

1

do

O

£

CsJ

.g>

CD

>

L.

CO

33

-

o

Q

O)

—

CO
• •

00

c

S__

a mamm

LL

-

o

CD

"5

CO

-

LU

LO

CM

CO

o

o

CM

CO

O

LO

CO

O

| 89 j ‘apn^iv O epoi/\|

Radio Communications with UA 175
[Compiled from FAA Transcripts, each source shown in brackets]

8:13:26 LCE

8:13:31 UAL-175

8:14:33 LCE
8:14:36 UAL-175
8:14:44 UAL-175

8:14:46 ID

8:14:51 UAL-175

8:15:41 ID

8:15:45 UAL-175

8:16:50 ID

8:16:53 UAL-175

8:17:09 ID

8:17:13 UAL-175

8:17:21 UAL-175

8:17:25 SL

8:17:28 UAL-175

8:19:08 SL

8:19:13 UAL-175

8:19:24 UAL-175

8:19:42 47R

8:19:48 UAL-175

8:22:06 47R

8:22:10 UAL-175

8:22:33 UAL-175

8:22:39 46R
8:27:09 47R
8:27:19 46R

8:27:28 UAL-175

8:27:34 UAL-175

United one seventy five heavy runway niner cleared for takeoff traffic's holding in
position on four right. [BOS 1202-1220 ICE]

cleared for takeoff runway niner Uniteds one seventy five heavy. [BOS 1 202-
1220 ICE]

United one seventy five heavy contact departure. [BOS 1202-1220 ICE]
departure Uniteds one seventy five heavy. [BOS 1202-1220 ICE]
departure Uniteds one seventy five heavy is with you out of twelve hundred.

[BOS 1209-1228 Initial Departure]

United one seventy five heavy Boston departure radar contact climb and

maintain one four thousand. [BOS 1209-1228 Initial Departure]

one four thousand Uniteds one seventy five heavy. [BOS 1209-1228 Initial

Departure]

United one seventy five heavy turn right heading two one zero. [BOS 1 209-1 228
Initial Departure]

turn two one zero Uniteds one seventy five heavy. [BOS 1209-1228 Initial
Departure]

United one seventy five heavy turn right heading two seven zero, pos 1209-
1228 Initial Departure]

turn to two seven zero Uniteds one seventy five heavy. [BOS 1209-1228 Initial
Departure]

United one seventy five heavy contact Boston approach one two seven point
two good day. [BOS 1209-1228 Initial Departure]

two seven point two Uniteds one seventy five heavy good day. [BOS 1209-1228
Initial Departure]

Boston good morning Uniteds one seventy five heavy is out of eight thousand.
[BOS 1211-1224 lincoln Departure]

United one seventy five heavy Boston approach fly heading two seven zero.
[BOS 1211-1224 lincoln Departure]

two seven zero on the heading Uniteds one seventy five. [BOS 121 1-1224
lincoln Departure]

United one seventy five heavy contact Boston center one three three point four
two. [BOS 1211-1224 lincoln Departure]

three three four two Uniteds one seventy five heavy good day. [BOS 1211-1224
lincoln Departure]

Boston good morning Uniteds one seventy five heavy heavy out of eleven seven
for one four thousand. [ZBW 1219-1230 Sector 47R]

United one seventy five Boston center dimb maintain flight level two three zero
you're deared direct BIGGO. [ZBW 1219-1230 Sedor 47R]
direct BIGGO up to two three zero United one seventy five heavy. [ZBW 1219-
1230 Sector 47R]

United one seventy five contad Boston center one two seven point eight two.
[ZBW 1219-1230 Sedor 47R]

two seven eight two United one seventy five so long. [ZBW 1219-1230 Sedor
47R]

Boston morning United one seventy five's out of uh nineteen for two three oh.
[ZBW 1222-1227 Sedor 46R]

United one seventy five Boston uh center roger. [ZBW 1222-1227 Sedor 46R]
United one seventy five you with me? [ZBW 1219-1230 Sedor 47R]

United one seventy five contad the ah Boston center on ah one three three
point four two. [ZBW 1222-1227 Sedor 46R]

'kay three four two United one seventy five so long. [ZBW 1222-1227 Sedor
46R]

Boston United ah one seventy five two three oh. [ZBW 1219-1230 Sedor 47R]

5

Radio Communications with UA 175
[Compiled from FAA Transcripts, each source shown in brackets]

8:27:37 47R
8:27:42 UAL-175
8:28:43 UAL-175
8:28:45 47R
8:28:49 UAL-175
8:28:52 47R

8:28:58 UAL-175

8:30:50 47R

8:30:56 UAL-175

8:31:04 UAL-175

8:31 .08 20R

8:37:03 20R
8:37:06 UAL-175
8:37:08 20R

8:37:18 UAL-175

8:38:00 20R

8:38:04 UAL-175

8:38:11 20R
8:38:24 20R

8:38:28 UAL-175

8:39:33 20R
8:39:36 UAL-175
8:39:41 20R

8:39:44 UAL-175

8:40:32 UAL-175

8:40:37 R42

8:41:28 UAL-175
8:41:31 R42
8:41:33 UAL-175

United one seventy five Boston center roger climb and maintain flight level three
five zero. [ZBW 1219-1230 Sector 47R]

up to three five zero we want to request three one zero if it's smooth for United
one seventy five. [ZBW 1219-1230 Sector 47R]

Boston Uniteds one seventy five like to request three one oh if it's smooth. [ZBW
1219-1230 Sector 47R]

United one seventy nine you say you want three one oh? [ZBW 1219-1230
Sector 47R]

yes sir if it's smooth for Uniteds one seventy five heavy. [ZBW 1219-1230 Sector
47R]

United one seventy nine maintain ah flight level that’s ah correction there I have
one seventy five maintain flight level three one zero. [ZBW 1219-1230 Sector
47R]

three one zero Uniteds one seventy five we'd like to keep that as a final. [ZBW
1219-1230 Sector 47R]

United one seventy five maintain three one oh and contact the Boston center on
one two five point five seven. [ZBW 1219-1230 Sector 47R]
two five five seven we'll maintain three one oh Uniteds one seventy five. [ZBW
1219-1230 Sector 47R]

Boston morning Uniteds one seventy five is out of two eight oh for three one oh.
[ZBW 1231-1239 Sector 20R]

United one seventy five Boston center roger good morning. [ZBW 1231-1239
Sector 20R]

United one seventy five Boston. [ZBW 1231-1239 Sector 20R]

one seventy five go ahead sir. [ZBW 1231-1239 Sector 20R]

roger do you have traffic look at uh your twelve to one o'clock at about uh ten

miles south bound see if you can see an American seventy sixty seven out there

please. [ZBW 1231-1239 Sector 20R]

okay were looking negative contact United one seventy five. [ZBW 1231-1239
Sector 20R]

okay United one seventy five do you have him at your twelve o’clock now and
five, ten miles. [ZBW 1231-1239 Sector 20R]

affirmative we have him uh he looks uh about ah twenty ah yeah about twenty
nine, twenty eight thousand. [ZBW 1231-1239 Sector 20R]
okay thank you. [ZBW 1231-1239 Sector 20R]

United one seventy five turn thirty degrees to the right I want to keep you away
from this traffic . [ZBW 1231-1239 Sector 20R]

thirty degrees to the right United one seventy five heavy. [ZBW 1231-1239
Sector 20R]

United one seventy five cleared direct SPARTA. [ZBW 1231-1239 Sector 20R]
direct SPARTA United one seventy five. [ZBW 1231-1239 Sector 20R]

United one seventy five contact New York center one two seven point one
seven. [ZBW 1231-1239 Sector 20R]

one two seven one seven United one seventy five. [ZBW 1231-1239 Sector
20R]

center good morning United one seventy five heavy three one oh. [ZNY 1237-
1307 Sector 42R]

United one seventy five * — correction United one seventy five New York center
roger. [ZNY 1237-1307 Sector 42R]

New York United one seventy five heavy. [ZNY 1237-1307 Sector 42R]

United one seventy five go ahead. [ZNY 1237-1307 Sector 42R]
ya we figured we'd wait to go to you center ah we heard a suspicious
transmission on our departure out of Boston ah with someone ah, ah sound like
someone sound like someone keyed the mike and said ah everyone ah stay in
your seats. [ZNY 1237-1307 Sector 42R]

6

Radio Communications with UA 175
[Compiled from FAA Transcripts, each source shown in brackets]

8:41:51

R42

8:41:55

UAL-175

8:42:12

UAL-175

8:51:42

R42

8:51:53

R42

8:52:09

R42

8:52:20

R42

8:53:52

R42

8:54:33

R42

oh okay I'll pass that along over here. [ZNY 1237-1307 Sector 42R]
that's ah cut out. [ZNY 1 237-1 307 Sector 42R]
did you copy that? [ZNY 1237-1307 Sector 42R]

United one seventy five recycle your transponder and squawk code of one four
seven zero. [ZNY 1237-1307 Sector 42R]

United one seventy five New York. [ZNY 1237-1307 Sector 42R]

United one seventy five do you read New York? [ZNY 1237-1307 Sector 42R]
United, United one seventy five do you read New York? [ZNY 1237-1307 Sector
42R]

United one seventy five New York. [ZNY 1237-1307 Sector 42R] .

United one seventy five do you read New York? [ZNY 1237-1307 Sector 42R]

7